Printer

ABSTRACT

A recording medium is wound on a roller shaft, a feed roller feeds the recording medium in a predetermined direction, a recording head assembly records information signals on the recording medium and a drive mechanism drives the recording head assembly to scan the recording medium. A spring is provided between the roller shaft and the feed roller to urge them to contact each other.

I O United States Patent 1191 1111 3,778,842

Saito Dec. 11, 1973 PRINTER 2,706,672 4/1955 Cooley 346/136 2,812,99711/1957 D' k t 346/139 R [751 Invent 5 l Yokwuka, Japan 3,389,402 6/1968116211221 11 1 346/145 x 1 T k 3,644,931 2/1972 Roland 346/139 R x [73]Asslgnee Sony corpora on, 0 Japan 3,139,320 6/1964 Johnson 346/145 [22]Filed: Sept. 27, 1971 [21] Appl. No.: 184,124 Primary Examiner-Joseph W.Hartary Att0rneyLewis H. Eslinger et a1.

[] Foreign Application Priority Data Sept, 29, 1970 Japan, /145450 57ABSTRACT [52] 346/136 346/74 SB 346/139 R A recording medium is wound ona roller shaft, a feed 51 Int. c1311. 0 0111 15/28 'ooid 15/24 filerfeeds the lemming medium in a predetermined [58] Field of S'earch346/139 R 136 74 CH direction, a recording head assembly recordsinforma- 346/74 E 74 S 74 74 tion signals on the recording medium and adrive mechanism drives the recording head assembly to scan the recordingmedium. A spring is provided between [56] References Cited the rollershaft and the feed roller to urge them to t t h 111 UNITED STATESPATENTS ac 0 2,355,502 8/1944 Barton 346/139 R 4 Claims, 20 DrawingFigures I L 1 IHIIIrIIIT IIJ lIIII PAIENIEBIIH: 1 1 ma SHEET 2 BF 9INVENTOR ET5UKO 541m PATENTEDOEC 1 1 I975 SHEET t Of 9 INVENTOR ET5UKO5A1 T0 PAIENIEMH: 1 I ma 3,778,842 sum 6 OF 9 IN VENT OR ET5UITO 5A1 T0PMENIH] DEC 1 1 I973 SHZET 8 CF 9 INVENTOR ETSU/TU 5/1170 PAIiNIEIlnm nma 3.778.842

SHEET 8 BF 9 IN VENTOR PRINTER BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to a printer, and more particularlyto a printer in which information signals are recorded by a recordinghead on a rolled recording paper with high speed.

2. Description of the Prior Art There has been proposed and put intopractical use a printer for data processing which is of the type thatpredetermined letters, numerals or figures are recorded by discharge,heating or electronically on a recording medium in one or. more linesper unit of time. In such a printer a recording head must be controlledto scan the recording medium for recording information signals thereon.To perform this, it is the practice in the prior art that the recordinghead is slidably mounted on a rotary shaft having a complicated camgroove and that the shaft is driven by a motor to cause the recordinghead to scan the recording medium in a predetermined direction. Duringthe recording stroke of the head (a head motion in a forward directionfor recording), the recording head must be held in contact with therecording medium but during the return stroke of the head (a head motionin a reverse direction toward its starting position) the head must beheld out of contact with the recording medium. For returning therecording head to its starting point, an electromagnet and othercomplicated means have heretofore been employed. Further, in order thatthe recording medium wound on a roller shaft may be drawn out in apredetermineddirection, the prior type printer adopts a method such thatthe recording medium is passed between a pair of feed rollers at leastone of which is supplied with a drive force. However, such a methodinvolves at least one pair of feed rollers, and hence inevitably leadsto bulkiness of the printer itself.

SUMMARY OF THE INVENTION The presentinvention of a printer comprises ahousing, a recording medium rotatably mounted in the housing, arecording head means for recording information signals on the recordingmedium, and means for causing the recording head means to scan therecording medium. The scanning means includes means for reciprocatingthe recording head means in a substantially straight line and means forengaging the recording head means with the recording medium forrecording the information signals thereon during a head motion in aforward directionand for disengaging the recording head means from therecording medium during a head motion in a reverse direction. Therecording medium is transported by feed roller means which contact therecording medium and by means for driving the feed roller means whichdraws out the recording medium from the housing when the recording headmeans is moved while being held out of contact with the recordingmedium.

In one preferred embodiment the drive means includes a rotatable firstcam and the scanning means includes a first arm engaged with the firstcam and connected to the recording head means, so that movement of therecording head means is caused by the rotation of the first cam toperform a straight reciprocating motion through the first arm. The drivemeans further includes a second cam and the scanning means also furtherincludes a second arm engaged with the second cam and connected to therecording head means, so that the recording head means is brought by therotation of the second cam into contact with the recording mediumthrough the second arm during the forward motion of the recording headmeans and is brought out of contact with the recording medium during thereverse motion of the recording head means.

In the first preferred embodiment the recording head means furtherincludes a support member slidably mounted on a rod fixed to the housingaccommodating the recording medium and a recording head fixed to thesupport member, the first and second arms being coupled to the supportmember apart from the rod. The recording medium has a recording paperand a conductive layer and the recording head means has needleelectrodes and the conductive layer is supplied with a current throughthe feeding means to thereby record information marks on the recordingpaper.

The primary object of this invention to to provide an improved printer.

Another object of this invention is to provide a printer in which arecording medium can be fed in a predetermined direction by theprovision of at least one feed roller.

Another object of this invention is to provide a printer in which a feedroller for feeding a recording medium in a predetermined direction andthe recording medium wound on a roller shaft are held in good contactwith each other regardless of the diameter of convolution of therecording medium to ensure stable feeding thereof.

Another object of this invention is to provide a printer in whichscanning of a recording head on a recording medium can be readilyachieved by the combined use of cams and actuating arms.

Another object of this invention is to provide a printer in which arecording medium can be readily set up in a printer housing.

Still another object of this invention is to provide a printer whichissmall in size, easy to handle and inexpensive.

Other objects, features and advantages of this invention will be morereadily understood from the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front view of a printerproduced according to this invention;

FIG. 2 is a plan view of the printer exemplified in FIG. 1;

FIG. 3 is a right side view of the printer of FIG. 1;

FIG. 4 is a left side view of the printer of FIG. 1;

FIG. 5 is a cross-sectional view taken along the line A--A in FIG. 1;

FIG. 6 is a cross-sectional view taken along the line BB in FIG. 2 withits cover being lifted and its head assembly being left out for the sakeof simplicity;

FIG. 7 is a bottom view of the printer depicted in FIG. 1, showing itshead scanning mechanism;

FIG. 8 is a perspective view of a recording medium wound on a rollershaft;

FIG. 9 is a plan view showing the relationship between a scanning armand a main cam;

FIG. 10 is a fragmentary cross-sectional view taken along the line C-Cin FIG. 1;

FIG. 11 is a longitudinal sectional view showing a sliding member;

FIG. 12 is a fragmentary cross-sectional view taken along the line D-Din FIG. 2;

FIG. 13 is a cross-sectional view of a gear bearing portion;

FIG. 14 is a graph showing the relationship between the movement of therecording head and the rotational angle of the main cam;

FIG. 15 is a side view schematically illustrating another example of theprinter of this invention;

FIG. 16 is a schematic plan view of the printer exemplified in FIG. 15;

FIGS. 17 and 18 are both exploded perspective views showing theprincipal part of the printer of FIG. 15',

FIG. 19 is a plan view of a cam employed in the printer of FIG. 15; and

FIG. 20 is a cross-sectional view taken along the line E-E in FIG. 19.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of this inventionwill be described in detail. In FIGS. 1 to 7, a printer housing I-Iconsists of a bottom plate 1, side panels 2a, 2b and 2c bent upwardlyfrom'the bottom plate 1 and a front panel 3 attached to the upper edgesof the side panels. In the present example these members are formed as aunitary structure of a sheet metal. A roller shaft 5, which is rotatablysupported by the side panels 2a and 2c in proximity to the front panel3, has mounted thereon a feed roller 4. The feed roller 4 is molded ofconductive rubber. The feed roller and its associated members will bedescribed later on.

Reference numeral 6 indicates generally a roll of recording paper whichis supported by the side panels 2a and 2b and whose periphery is snuglyurged against the feed roller 4. The so-called conductive recordingpaper 7 of a predetermined width is wound on a roll 8, which is providedwith shafts 9 projecting out from both end faces thereof as shown inFlG.8. The recording paper 7 is of a known type, with which a plurality ofneedle electrodes are held in contact for recording. When supplied withcurrents from the needle electrodes, the recording paper 7 is heated orelectrolyzed or blown off to form tiny holes at the contacting points ofthe recording paper with the needle electrodes, thereby to providevisible information. The present example employs a recording paper suchthat its base is colored and then deposited with a conductive film as ofaluminum. Supplied with currents from the needle electrodes, only thealuminum film is fused instantaneously to form an image with dotscorresponding to the needle electrodes.

As shown in FIGS. 4 and 6, the panels 2a and 2b have respectively formedtherein substantially L-shaped guide notches 10, each consisting of avertical notch 10a which is open to the upper edge of the side panel anda horizontal notch 10b which extends a little upwardly from the verticalnotch 10a by a predetermined length towards the forward portion of theside panel. Further, the side panels 2a and 2b are respectively providedwith pivots 12, which have mounted thereon pushing arms 11 respectively.The arms 11 are mounted'on the outsides of both the side panels 2a and2b symmetrically with each other together with intercoupling linksdescribed later on. The guide notches 10 mentioned above receive theshafts 9 of the roll 8 with the recording paper 7 wound thereon. Thepaper roll 6 may be loaded in position by inserting its shafts 9 intothe guide notches 10 from its vertical notches 10a (FIG. 6). Further,each of the arms 11 has formed therein a notch 11a extending down fromthe upper edge thereof, which receives the shaft 9. That is, under theconditions depicted in FIG. 6, the shaft 9 is rested on the bottom ofthe .vertical notch 10a and positioned in the notch 11a. In order tobring the paper roll 6 into such a condition, a side piece 11b of thearm 11 forwardly of the notch Ila is formed shorter than a side piece11c rearwardly of the notch 11a.

Further, as depicted in FIGS. 4 and 6, pins 13a and 13b are planted oneach of the side panels 2a and 2b and each of the arms 11 respectivelyand a bias means, in this case, a coiled spring 13 is provided betweenthe pins 13a and 13b with the pin 12 therebetween for biasing the arm 11towards the feed roller 4. Under such conditions, when the arm 11 isturned by the coiled spring 13 in the direction of the feed roller 4,the shaft 9 is moved forward, guided by the horizontal notch 10b tobring the surface (the recording surface) of the recording paper 7 intocontact with the circumferential surface of the feed roller 4 (FIG. 2)and the recording paper 7 is always urged by the arm 11 against the feedroller 4 at a suitable pressure irrespective of variations in thediameter of the convolution of the recording paper 7.

Referring again to FIGS. 4 and 6, a cover 14 of a U- shaped crosssection for covering the upper open end portion of the housing H isattached to the side panels 2a and 2b through a support frame 15 securedto the inside of the backward portion of the cover 14 and hinged aboutpins 16. In FIG. 6 the printer housing H is shown by solid and chainlines to be in its opened and closed conditions. When the printerhousing H is open, the rear edge portion is rested on projections 2 ofthe side panels. The aforementioned link 17 is pivoted by a pin 19 tothe support frame 15 in proximity to the cover 14 from the outsidethereof. The link 17 is substantially L-shaped and has an elongatedopening 17a formed in its longer arm portion for engagement with aguidepin l8 planted on the extremity of the rear side piece of the arm11 to interconnect the cover 14 and the arm 11.

With'reference to FIG. 6 a description will be given of associatedoperations of the arm 11, the cover 14 and the link 17. When the cover14 is lifted, the arm 11 is turned clockwise through the link 17 topermit loading (or unloading) of the rolled recording paper 7. Undersuch conditions, the line XX joining the pin 19 of the link 17 with theguide pin 18 lies below the center of the pin 16 of the support frame15. That is, the cover 14 rested on the projections 2' of the sidepanels 2a and 2b is held in its lifted position. It will be readilyunderstood that, turning the cover 14 to cover the printer housing II,when the aforementioned line XX has passed the pin 16, the cover 14 ispulled by the biasing force of the arm 11. Namely, pushing the cover 14forwardly simultaneously with loading of the rolled recording paper 7,the cover 14 is snapped down to cover the housing H and, at the sametime, the rolled recording paper 7 is also pushed forward by the forwardmovement of the shafts 9. Between the front edge 14' of the cover 14 andthe front panel 3 there is defined a gap 20 (refer to FIG. 2), throughwhich the revide a blade 3. However, it is a matter of course that sucha blade may be provided separately.

In FIGS. 4 and 6 the arm 111s shown to have a notch 11d in its frontmarginal portion which serves as a relief from a pin having affixedthereto one end of a spring described later on. However, such a notch11d need not be formed in the arm mounted on the side plate 2b but inthe present example two arms punched in the same configuration areemployed symmetrically.

A recording means and more particularly, a scanning mechanism, will nowbe described.

In the foregoing, the feed roller 4 and the roller shaft 5 have beenoutlined. Theroller shaft 5 is supported bythe side panels 2a and 2b(bearings therefor not shown) while being electrically insulatedtherefrom. The righthand portion of the roller shaft 5 has mountedthereon a pinion 21 adjacent to the feed roller 4 and a manual feed knob22 on the side of the side panel 2c, between which a spring brush 23 asof phosphorous bronze sheet is held in contact with the roller shaft 5(refer to FIG. 5), the spring brush 23 being electrically connected witha terminal 24 mounted on the upper surface of the front panel 3.Further, a head support frame 25, which is U-shaped in cross-section andwhose side pieces 25a and 25b extend upwardly, is disposed inside of theside panels 2a and 2c. The support frame 25 is provided with a lowerguide rod 26 which is passed through the side pieces 25a and 25b andsecured at both ends to the side panels 2a and 2c and about which thesupport frame 25 is turned and an upper guide 27 is bridged between theupper portions of the side pieces 25a and 25b. A recording head assembly32 is slidably supported by the guide rods 26 and 27 and springs 29 aresecured at one end to both of the projecting portions of the upper guiderods 27 and at the other end to pins 30 planted on the outside of theside panels 2a and 20, thereby to bias the head .support frame 25rearwards, and in order to limit the rearward movement of the supportframe 25, both of the projecting ends of the guide 27 and 26 to movethereon to right and left in FIG. 1

and a head 32 mounted on the sliding member 31. In the present example,the head 32 is obliquely mounted on the sliding member 31 as shown inFIG. 2 and the front of the head 32 has attached thereto, for example,nine needle electrodes 33. From the back of the head 32 are led outcoated lead wires 32 (indicated by broken lines for convenience ofillustration) which are connected to the needle electrodes 33respectively. These lead wires 34 are sufficiently flexible and disposedin a manner not to interfere with the reciprocating motion of therecording head assembly 28. The needle electrodes 33 are the same lengthand suitably spaced from one another and are adapted to be urged againstthe surface of the recording paper 7 at a predetermined pressure duringthe recording stroke of the head, that is, the head motion in theforward direction for recording.

A mechanism is provided for the reciprocating motion of the recordinghead assembly 28. That is, in

tance d as indicated by solid and broken lines (but the FIGS. 2, 3, 4and 7, a motor 35 is mounted on the bottom plate 1 and a pinion 36 isaffixed to a shaft 35' of the motor 35 and meshed with a gear 37. Thegear 37 is rotatably mounted on a gear support shaft 38 fixed on thebottom plate 1 (refer to FIG. 13) and bosses of the gear 37 formed onits upper and lower surfaces have fixed thereto a main cam 39 and anauxiliary cam 40 which are spaced a predetermined distance apart fromeach other. The gear support shaft 38 has a flange 38' at its top end,which is attached to the upper surface of the bottom plate 1 so that theshaft projects down through the bottom plate 1. The main and auxiliarycams 39 and 40 are both plane cams, namely peripheral cams and adaptedto cause their cam followers to follow their curved peripheral surfacesand the phases of the earns 39 and 40 are also selected as desired.

In FIGS. 7 and 9 reference numeral 41 indicates a scanning arm which isa cam follower of the main cam 39 and a head releasing arm 42 which is acam follower of the auxiliary cam 40 and crosses the arm 41substantially at right angles thereto. These arms 41 and 42 have mountedthereon rollers 41a and 42a respectively, which are urged against theperipheral surfaces of the cams 39 and 40 respectively, so that thescanning arm 41 is turned about a pivot 43 mounted at the back portionof the bottom plate 1 and the head releasing arm 42 is turned about apivot 44 planted on the bottom plate 1. I

The scanning arm 41 included of a main lever 41b associated with theaforementioned sliding member 31 and an auxiliary lever 410 foractuating a rocking lever described later on. The main lever 41b is bentup near its free end portion and the free end portion is, in turn, bent(refer to FIG. 10), on which a guide member 45 is mounted. A roller 46is attached to the free end of the auxiliary lever 410. Further, amagnet 71 is mounted on the main lever 41b in the vicinity of its bentportion.

The aforementioned sliding member 31 included a block 31a carrying thehead 32 and aplate-like member 31b extending down from the left-handportion of the block 31a as viewed in FIGS. 1 and 11. A sleeve 31c, intowhich the upper guide rod 27 can be smoothly inserted, is forced intothe block 31a in a direction perpendicular to the plate-like member 31band a U- shaped groove 31d is formed in the plate-like member 31b forreceiving the lower guide rod 26 with a little play. Further, the block310 has formed therein a substantially cross-shaped slide groove 31ewhich is open to the underside of the block 31a and the guide member 45of the scanning arm 41 is inserted into the slide groove 31e. Namely,the guide member 45 is shaped to conform to the slide groove 31e and isslid therein back and forth to guide the sliding member in response tothe movement of the scanning arm 41. That is to say, the movement of thescanning arm 41 is a rotational one, which is converted into a straightmotion by the guide rods 26 and 27 and the slide groove 31e of thesliding member 31.

FIG. 9 shows the relationship between the main cam 39 and the scanningarm 41. During one cycle (one rotation) of the main cam 38 the guidemember 45 mounted on the free end of the main lever 41b performs areciprocating motion over a straight disstarting point of the motion isset separately). This reciprocating motion is converted into that of thescanning head assembly 28 through the sliding member 31 but the main cam39 is designed'based on such conditions as depicted in FIG. 14, in whichthe abscissa represents the rotational angle of the main cam 39 and theordinate the aforementioned distance d. The reciprocating motion of themain cam 39 during one cycle is divided into a straight and uniformrecording motion and a sinusoidal returning motion and the recordingmotion is stopped at y in the vicinity of 240 and the starting point ofthe reciprocating motion is established at about 240 (indicated by anarrow X As is apparent from FIG. 14, the recording motion is a uniformone and that the returning motion is smooth and quick. The reciprocatingmotion initiating point X will hereinbelow be described.

The bearing structure of the pivot 43 of the scanning arm 41 is such asdepicted in FIGS. 2 and 12. The pivot 43 is inserted into a flangedcylindrical bearing 47, both of which are exposed on the bottom plate.The pivot 43 projects out a little from the upper end of the bearing 47.A slit 43a for retaining one end of a spring is formed in the projectingend of the pivot 43 and a coiled spring 43 is loosely wound on thebearing 47 and retained at its upper end in the slit 43a. The lower endof the spring 47 is retained by a tab 1' of the bottom plate 1, tothereby'bias the scanning arm 41 clockwise as viewed in FIG. 2. Thus, itwill be understood that the starting point X is so selected as topromote the starting torque of the motor 35 with the biasing force ofthe scanning arm 41 at the starting of the reciprocating motion.

As shown in FIGS. 5 and 7, a first rocking lever 49, which is pivotallymounted by a pin 50 on the upper portion of the side panel 20, is bentinwardly at right angles at its lower end portion to provide a tab 49a.The tab 49a engages the roller 46 of the scanning arm 41 as shown inFIG. 7. The rocking lever 49 is biased by a coiled spring 51 clockwiseas viewed in FIG. 5. A second rocking lever 52 is-journalled by a pin 53to the side panel 2c and has a rectangular opening 52a formed in itslower portion. Since the tab 49a is engaged with the roller 48 of thescanning arm, the first rocking lever 49 is turned counter-clockwisethrough a predetermined angle in the direction of an arrow as viewed inFIG. 5 when the scanning arm 41 is returned. Further, an engaging piece42b formed at the free end portion of the aforementioned releasing arm42 isinserted into the rectangular opening 52a of the second rockinglever 52 and when the releasing arm 42 is turned by the auxiliary cam40, the second rocking lever 52 is also turned through a predeterminedangle in the direction indicated by the arrow in FIG. 5. The first andsecond rocking levers 49 and 52 project downwardly through holes 54 and55 in the bottom plate 1.

Referring now more particularly to FIG. 1, a gear 56 is meshed with thepinion 21 of the roller shaft 5, by which the rollershaft 5 isintermittently driven through the pinion 21. A ratchet wheel 57 formedintegrally with the gear 56 and the ratchet wheel 57 and the gear 56 arerotatably mounted on a shaft 58 secured to the side panel 2c and a pawl59 is engaged with the ratchet wheel 57, as shbwn in FIGS. 1 and 5. Aninverted U- shaped rocking piece 60 is mounted on the shaft 58, a pin 61is attached to the lower end of the rocking piece 60 and the base of thepawl 59 is pivoted to the pin 61. A bias spring 62 is secured at itsmiddle to the pin 61 and at its ends to a link 63 which interconnectsthe pin 61 with the first rocking lever 49. The turning of the rockinglever 49 is thus converted into intermittent rotation of the ratchetwheel by the pawl 59. This intermittent rotation of the ratchet wheel 57is transmitted to the pinion 21 through the gear 56, so that the feedroller 4 coaxial with the pinion 21 pays out the recording paper 7intermittently and at a constant pitch. Reference numeral 64 indicates apin on the rocking arm 49 to which is pivoted the link 63.

Further, a coupling piece 250 is formed on the head support frame 25near its side piece 25b and is coupled with the second rocking lever 52through a link 65 which is pivoted by a pin 67 to the rocking lever 52and by a pin 66 to the piece 25c. When the rocking lever 52 turns, thehead support frame 25 turns about the lower guide rod 26 in a clockwisedirection, that is, in the direction indicated by an arrow as viewed inFIG. 5.

In FIGS. 1, 3, 5 and 7 reference numeral 68 represents a terminal plateattached to the bottom plate 1 with spacers 69a and 69b interposedtherebetween near the front edge of the bottom plate 1. Reed switches70a and 70b are disposed on the terminal plate 68 at right and leftpredetermined positions. These reed switches are closed by the magnet 71mounted on the scanning arm 41 and for detecting the recordinginitiating and terminating positions of the scanning head assembly 28.The detected signals are transmitted to a computer.

The foregoing description has been with respect to the construction ofthe printer mechanism of this invention. The following description willbe made in connection the recording operations of the printer of thisinvention.

The printer is associated with a computer and the motor 35, the terminal24 for impressing a power source voltage to the recording paper 7, thereed switches 70a and 70b etc., are connected to predetermined electriccircuits and the lead wires 34 of the recording head assembly 28 areconnected to the recording circuits of the computer. The rolledrecording paper 7 is loaded in the recording device in the mannerpreviously described. In this case, the recording paper 7 is initiallypaid out through the gap 20 by turning the knob 22. The computer is thenoperated as predetermined to set the printer in its recording conditionto close the circuit of the motor 35. When the motor 35 is thusenergized, the rotation of the shaft of the motor 35 is transmitted tothe main and auxiliary earns 39 and 40 through the gear 37. When theroller 41a of the scanning arm 41 engages the main cam 39 at thesmallest diameter portion thereof, the head assembly lies at theleft-hand end on the guide rods 26 and 27 as viewed in FIG. 2. Withclockwise turning of the main cam 39, the scanning arm turnsanticlockwise, by which the scanning head assembly 28 is also moved onthe guide rods 26 and 27 from left to right.

At this time, voltages corresponding to signals from the computer areimpressed between the individual needle electrodes 33 and the recordingpaper 7 to cause a discharge therebetween, to thereby to record on therecording paper 7, letters, marks and the like corresponding to thesignals. In the case that the smallest diameter portion of the main cam39 engages its cam follower, the rotational angular position of the maincam 39 is 0 as shown in FIG. 14, and recording is achieved from the 0position to that spaced 7 apart therefrom. As will be seen from FIG. 14,the diameter of the cam 39 varies linearly. During recording, thediameter of the auxiliary cam 40 does not change. When the roller 41a ofthe arm 41 turns into contact with the largest diameter portion of themain cam 39, the larger diameter portion of the auxiliary cam 40 turnsinto contact with the roller 42a of the releasing arm 42. Accordingly,the releasing arm 42 is turned by the auxiliary cam 40 to left in FIG.7, by which the rocking lever 52 is turned clockwise through the top endportion 42b of the arm 42 as indicated by the phantom line in FIG. 5.The link 65 coupled to the lever 52 moves to right in FIG. 5 to turn thehead support frame 25 clockwise abut the guide rod 26, thus disengagingthe head assembly 28 from the recording paper 7. The largest diameterportion of the auxiliary cam 40 is selected to cover the range in whichthe diameter of the main cam 39 varies from its maximum to minimumvalue.

Since the change in the diameter of the main cam 39 from the maximum tothe minimum is abrupt as shown in FIG. 14, the scanning arm 41 rapidlyturns clockwise in FIG. 2 and consequently the head assembly 28 isbrought from right to left as shown in FIGS. 1 and 14. During thisleftward movement the head assembly 28 is held out of contact with therecording paper by the actions of the auxiliary cam 40 and the link 65.During the returning stroke of the head assembly 28, the auxiliary arm410 of the scanning arm 41 turns clockwise as 1 depicted-in FIG. 2, sothat the roller 46 abruptly pushes down the projection 49a of the firstrocking lever (to left in FIG. 5) and the ratchet wheel 57 is therebyturned by one pitch through the pawl 59 associated with the link 63. Thearm 41 engaging the smallest diameter portion of the main cam 39 throughthe roller 41a is so moved as to bring the head assembly 28 from theleft-hand end to the right-hand end and the auxiliary cam 40 returns thelever 42 to its initial position to bring the head assembly 28 intocontact with the recording paper 7.

The foregoing operations are repeatedly carried out for recordinginformation on the recording paper and the diameter of convolution ofthe recording paper 7 decreases with the progress of the recording. Inthe present invention, however, either one of the roller shafts 9 of therecording paper 7 is always biased by the spring 13 through the arm 11in the direction of the feed roller 4 to ensure that the recording paper7 is alv'vays held in good contact with the feed roller 4. Consequently,the recording paper 7 is paid out in a predetermined directionirrespective of the diameter of its convolution. Thus, the recordingpaper 7 is paid out by the peripheral surface of the feed roller 4 aspreviously described. Of course, the amount of the recording paper 7paid out corresponds to the spacing between lines of the informationrecorded. Further, the starting torque of the motor 35 is promoted bythe biasing force im- I from the foregoing example, the printer of thisinvention is of extremely simple construction, which leads to thesubstantial reductions in size and in weight and enables mass productionto curtail the manufacturing cost. v

A description will be given of another embodiment of this inventionwhich is smaller in size than the foregoing example. In FIGS. 15 to 18 ahousing H included of a bottom plate 101 and side panels 102a, 102b and102c vertically bent up from the bottom plate 101. A shaft 105 of arecording paper feed roller 104 is rotatably supported by the sidepanels 102a and 102b. The feed roller 104 is formed of a conductiverubber to serve as an electrode for the recording paper and is suppliedwith a current through a slip ring 106. A rolled recording paper 107 hascentrally disposed shafts 108 and the recording paper is paid out by thefeed roller 104 in the direction indicated by the arrow (in FIG. 15). Apair of arms 109 are rotatably mounted on a rotary shaft 110 and theirfree ends are fork-shaped to hold a roller shaft 108 therebetween. Thearms 109 are biased clockwise by coiled springs 111 arranged between thearms and the side panels 102a and l02b respectively to push therecording paper roll 107 towards the feed roller 104 at all times. Apair of guide notches 112 are formed in the side panels 102a and 102bfrom their upper edges respectively to guide the roller shaft 108towards the feed roller 104.

Reference numeral 113 indicates generally a recording head assembly(FIG. 15). A plurality of, for example, nine needle electrodes 114 arearranged side by side on a head 115 in the scanning direction thereof.The head 115 is secured to a sliding member 116 and a terminal plate 117is attached to the outer side of the sliding member 116. Pins 118 aremounted on the terminal plate 117 and are interconnected to the separateneedle by lead wires 119. The underside of the sliding member 116 hasformed thereon a downwardly projecting but bent sliding portion 116a, ahole being formed in the free end of the sliding portion 116a in thescanning direction thereof. A similar hole is formed in the slidingmember 116. These holes are slidably engaged with guide rods 120 and 121respectively. The guide rod 121 is supported between tabs 122 of theside panels 102a and 1020. A support frame 123 of the recording headassembly 113 is pivotally mounted on the guide rod 121 at the tabs 122.The support frame 123 is U-shaped in cross-section and its arms are bentin the form of a shallow V. The upper free ends of the arms support theguide rod 120 therebetween. Consequently, the guide rods 120 and 121 aresupported at the upper and lower end portions of the bent armsrespectively. That is, the support frame 123 support the recording headassembly 113 with the guide rods 120 and 121 at the sliding member 116and the sliding portion 116a respectively. Between the bent arms and theside panels 102a and 102c coiled springs 124 are provided respectivelyto push the recording head assembly 113 towards the recording paper roll107, thereby to urge the needle electrodes 114 against the recordingpaper at a suitable pressure. The contact positions of the needleelectrodes 114 with the recording paper roll 107 lie above theaforementioned feed roller 104 in FIG. 15, that is, near the end of therecording paper as indicated by 107a. With such an arrangement, thesurface of the recording paper after recording information thereon isnot stained by the feed roller 104 and the recording information can beobserved immediately after recorded.

A rectangular window 125 is provided between the recording surface ofthe recording paper 107 and the needle electrodes 114 inthe scanningdirection of the head assembly 113, the window 125 being fixed at bothends to the side panels 102a and 102b. This window 125 is formed of, forexample, a thin metal sheet and is designed so that at the terminationof scanning the needle electrodes 114 slide a little on the frame of thewindow to clear off dust therefrom, ensuring that informationis recordeddistinctly by the subsequent record ing. Further, the feed roller 104 iscovered with a plate so as not to be stained by the dust.

A description will be given of a drive mechanism. A constant-speed drivemotor 126 is provided which is supported by the side panel 1020 andwhose rotary shaft is supported by a bearing disposed on the bottomplate 101. cam plate 127 is associated with the drive motor l26.j Thecam plate 127 is disc-shaped and formed of, for example, a plasticmaterial, which plate has a rotary shaft disposed centrally thereof andis driven at a constant speed by the drive motor 126 through, forexample, a belt 129 in a clockwise direction in FIG. 16. As shown inFIGS. 19 and 20, the cam plate 127 has formed therein first and secondcams 131 and 132. The first cam 131 is in the form ofa deformedheart-shaped groove and the second cam 132 is formed along the peripheryof the cam plate 137 over an angular range of, for example, 155 in amanner not to be flush with the upper surface of the cam plate 127.

First and second arms 135 and 136 are provided in engagement with thefirst and second cams respectively. One end of a main side 138 of thefirst arm 135 is pivoted to a rotary shaft 137 and the other end isfixed to the underside of the sliding member 116 of the recording headassembly 113. Further, the first arm 135 has branch sides 139a, 13% and1390 which are arranged to form a trapezoid with the main side 138 nearthe rotary shaft 137 and a side 139d is obliquely branched out from thejoint of the sides 139a and 13%. At the joint of the sides 13% and 13% acam roller 140 is rotatably supported and engaged with the first cam 131and pins 141 and 142 are mounted near the.

joint of the sides 139a and 13% and at the free end of the side 139drespectively. A third arm 143 described in detail later is pivoted tothe pin 141 and a coiled spring 144 is provided between the pin 142 andthe side panel 1020 to bias the first arm 135 about the rotary shaft 137clockwise in FIG. 16. Though not shown, lead wires for supplying signalsto the needle electrodes 114 are led along the first arm 135 to theneedle electrodes 114 from connecting terminal pins detachably mountedon the backof the printer, so that the lead wires move about the rotaryshaft 137 following the motion of the needle electrodes 114.Accordingly, the lead wires need not be unnecessarily long and shall notbe forcibly pulled. The first arm 135 is moved by the roller 140 engagedwith the first cam 131 in such a manner that the recording head assembly113 performs the recording motion (indicated by a solid line) and thereturning motion (indicated by a broken line) over a distance d.Further, the second arm 136 carries a roller 145 at one end contactingthe cam plate 127 and is rotatably supported at the other end by a pin146 provided on the support frame 123 on the side ofthe side panel 102a.During the return stroke of the recording head assembly 113, the roller145 is engaged with the second cam 132 to turn the support frame 123against the biasing force of the coiled spring 124 in such a manner thatthe recording head assembly 113 is held out of contact with therecording paper 107. Accordingly, the

angular range of the cam 132 is selected to comply with this. On the camplate 127 magnets 133 and 134 are affixed (refer to FIGS. 19 and 20) fordetecting the starting and terminating points of the recording stroke ofthe recording head assembly 113 respectively. That is, magnetosensitiveelements are provided on a stationary part corresponding to the magnetsrespectively, though not shown. With pulses induced in circuits of themagnetosensitive elements, the initiation and termination of therecording are detected, according to which supply of signals to theneedle electrodes 114 is controlled.

The following will describe a mechanism for feeding the recording paper107. This mechanism includes a third arm 143, a ratchet wheel 147 and apinion 148 attached to the feed roller shaft 105. The third arm 143 iscoupled with a link arm 150 (FIGS. 16 and 17) pivoted to a rotary shaft151 of the ratchet wheel 147 and a click 152 is mounted on the link arm150. The click 152 is engaged with the ratchet wheel 147 to drive it atevery rotation of the cam plate 127, that is, at every reciprocatingmotion of the third arm 143. Teeth 147a of the ratchet wheel 147 aremeshed with the pinion 148 to drive the feed roller shaft in a manner tofeed the recording paper 107 by the length of one line for recording atevery rotation of the cam plate 127, and accordingly at every completionof the recording stroke of the recording head assembly 113. On theratchet wheel 147 a manual feeding knob 149 is mounted on the side ofthe side panel 1020 and a pawl (not shown) is provided on the inside ofthe knob 149. By driving the ratchet wheel 147 with the pawl, therecording paper can be freely paid out. With such an arrangement, notrouble is caused in the automatic recording paper feed mechanism evenby an accidental touch on the manual feeding knob 149 during operationof the printer.

In FIG. 17 a cover 200 for covering the housing H and a lever 201 forcoupling the cover 200 with the housing H are provided. In this figurereference numeral 203 designates an upper panel, which is provided witha cutter 204 for cutting the recording paper 107.

While the foregoing has described the construction of the printer of thepresent example and the operations of its respective mechanisms, adescription will be given of general recording operations. That is, theprinter is associated with a computer, a drive motor 126 is connected toa power source and the recording head 113, the feed roller shaft 105 andthe magnetosensitive elements are connected through connectors torespective signal terminals of the computer. The recording paper 107 isinitially loaded in the recording device and is suitably paid out byturning the manual feeding knob 149. Then, the computer is operated tobring the printer in its recording conditon, in which a predeterminedvoltage si impressed to the recording paper 107 and, at the same time,the circuit of the motor 126 is closed. This operation is substantiallythe same as that of the foregoing embodiment. Further, in the presentembodiment, when the recording head 113 starts recording from itsstarting point after the return stroke, the roller of the second arm 136disengages from the second cam 132 to urge the recording head 113against the rolled recording paper 107, namely to bring the needleelectrodes into contact with the recording paper 107 and, at the sametime, signals are supplied to the needle electrodes 114 by a recordinginitiating signal induced in the magnetosensitive element correspondingto the magnet 133. The first arm 135 engages the first cam 131 to causethe recording head 113 to start its recording stroke. During therecording stroke, the needle electrodes 114 record information on therecording paper in accordance with the signals fed from the computer. Atthe end of the recording stroke a signal representing the completion ofthe recording is induced in the circuit of the magnetosensitive elementcorresponding to the magnet 134'to stop the supply 'of the recordingsignal from the computer. The first arm 135 then brings the recordinghead 113 in its return stroke corresponding to engagement of the firstarm 135 with the first cam 131 and, at the same time, the second arm 136engages the second cam 132 to turn the support frame 123 to disengagethe recording head 113 from the recording paper 107. Following this, thethird arm 143 pivoted to the pin 141 is brought towards the front-of theprinter (FIG. 16) corresponding to rocking of the side portion 139d ofthe first arm 135, by which the coupling portion of the third arm 143with .the link arm 150 is pushed down towards the underside of theratchet wheel 147 to cause the pawl attached to the link arm 150 to turnthe ratchet wheel 147 anticlockwise (as viewed in FIG. 16) by one step.As a result of this, the feed roller shaft 105 is turned by the pinion148 to pay out the recording paper 107 by the length of one line. Thus,the recording head is returned to its starting point and thereafter therecording and return stroke of the recording head are repeatedly carriedout in the same manner.

According to the present example, the first cam is so formed as toperform the recording motion at a uniform speed and during the returnstroke the recording head is held out of contact with the recordingpaper to avoid distortion of the record and prolong the service life ofthe recording head. Further, since the lead wires of the recording headare arranged along the first arm, they are not unnecessarily pulledduring the scanning operation of the recording head. In addition, thepawl is provided on the manual recording paper feeding knob, so thateven if the operator accidentally touches the knob by hand, no troubleoccurs. Furthermore, the printer can be simplified as a whole and can bereduced in size and in weight.

The present invention is not limited specifically to the foregoingexamples and may be modified variously within the spirit of thisinvention. Of course, the present invention may be used with not onlythe electric recording system but also a heat recording system employinga heat-sensitive recording paper. Further, the present invention isapplicable to recording apparatus of various instruments other than deskelectronic computers and registers.

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts of thisinvention.

I claim as my invention:

1. A printer comprising a housing accommodating a recording medium woundon a roller shaft, means for feeding the recording medium in apredetermined direction, a drive source for driving the feeding means, arecording head means for recording information signals on the recordingmedium, means for causing the recording head means to scan the recordingmedium, and means for shifting the recording medium and the feedingmeans in opposite directions to bring them into contact with each other,wherein the drive source includes a rotatable first cam and the scanningmeans includes a first arm engaged with the first cam and connected tothe recording head means, so that the recording head means is caused bythe rotation of the first cam to perform a straight reciprocating motionthrough the first arm, and the drive source further includes a secondcam and the scanning means also further includes a second arm engagedwith the second cam and connected to the recording head means, so thatthe recording head means is brought by the rotation of the second caminto contact with the recording medium through the second arm during theforward motion of the recording head means and is brought out of contactwith the recording medium during the reverse motion of the recordinghead means.

2. A printer as claimed in claim 1, wherein the recording head meanscomprises a support member slidably mounted on a rod fixed to thehousing accommodating the recording medium and a recording head fixed tothe support member, the first and second arms being coupled to thesupport member apart from the rod.

3. A printer comprising a housing, a first lever having one free end andone end pivoted on the housing, a recording medium, the recording mediumbeing wound on a roller shaft which is removably mounted on the free endof the first lever, a cover pivoted on the housing along a substantiallyhorizontal axis to cover the wound recording medium, the cover having alink lever pivoted at one end to the housing at a first point andconnected by a guide pin at its other end to the free end of the firstlever, theposition of the link lever being such that when the cover isin an open position a line extending from the guide pin to the firstpoint passes beneath the horizontal axis about which the cover pivots onthe housing, recording head means movably mounted on the housing, feedroller means mounted on the housing, and spring bias means for biasingthe first lever in a direction toward the feed roller means and to thehead means, such that when the cover is closed so as to cover the woundrecording medium, the wound recording medium is engaged with the feedroller means and with the head means, and when the cover is opened thefirst lever is pulled by the link lever away from the feed roller meansand locked in an open position by the weight of the cover so that thewound recording medium is retracted from engagement with the feed rollermeans and head means and can be taken out from the first lever.

4. A printer as recited in claim 3 wherein the housing is provided withguide notches to at least partially support the roller shaft on therecording medium and a second lever corresponding to the first lever isprovided to contact an end of the roller shaft opposite to the firstlever.

1. A printer comprising a housing accommodating a recording medium woundon a roller shaft, means for feeding the recording medium in apredetermined direction, a drive source for driving the feeding means, arecording head means for recording information signals on the recordingmedium, means for causing the recording head means to scan the recordingmedium, and means for shifting the recording medium and the feedingmeans in opposite directions to bring them into contact with each other,wherein the drive source includes a rotatable first cam and the scanningmeans includes a first arm engaged with the first cam and connected tothe recording head means, so that the recording head means is caused bythe rotation of the first cam to perform a straight reciprocating motionthrough the first arm, and the drive source further includes a secondcam and the scanning means also further includes a second arm engagedwith the second cam and connected to the recording head means, so thatthe recording head means is brought by the rotation of the second caminto contact with the recording medium through the second arm during theforward motion of the recording head means and is brought out of contactwith the recording medium during the reverse motion of the recordinghead means.
 2. A printer as claimed in claim 1, wherein the recordinghead means comprises a support member slidably mounted on a rod fixed tothe housing accommodating the recording medium and a recording headfixed to the support member, the first and second arms being coupled tothe support member apart from the rod.
 3. A printer comprising ahousing, a first lever having one free end and one end pivOted on thehousing, a recording medium, the recording medium being wound on aroller shaft which is removably mounted on the free end of the firstlever, a cover pivoted on the housing along a substantially horizontalaxis to cover the wound recording medium, the cover having a link leverpivoted at one end to the housing at a first point and connected by aguide pin at its other end to the free end of the first lever,theposition of the link lever being such that when the cover is in anopen position a line extending from the guide pin to the first pointpasses beneath the horizontal axis about which the cover pivots on thehousing, recording head means movably mounted on the housing, feedroller means mounted on the housing, and spring bias means for biasingthe first lever in a direction toward the feed roller means and to thehead means, such that when the cover is closed so as to cover the woundrecording medium, the wound recording medium is engaged with the feedroller means and with the head means, and when the cover is opened thefirst lever is pulled by the link lever away from the feed roller meansand locked in an open position by the weight of the cover so that thewound recording medium is retracted from engagement with the feed rollermeans and head means and can be taken out from the first lever.
 4. Aprinter as recited in claim 3 wherein the housing is provided with guidenotches to at least partially support the roller shaft on the recordingmedium and a second lever corresponding to the first lever is providedto contact an end of the roller shaft opposite to the first lever.